The microphone assembly comprises a MEMS (micro-electromechanical system) dual backplate microphone. The MEMS dual backplate microphone is configured to provide a differential signal. Differential signaling is a method of transmitting information electrically with two complementary signals sent on two paired paths. Since external interference tend to affect both paths together, and information is sent only by the difference between the signals, the technique improves resistance to electromagnetic noise compared with use of only one signal.
The common mode rejection ratio (CMRR) of a differential microphone assembly is the ratio of the rejection of unwanted input signals common to both signal paths, relative to the wanted differential signal. To increase the CMRR in a differential microphone assembly, the differential gain between the signals has to be maximized and the common mode gain has to be minimized.